[donmcpeters]

Greetings, all!

I have a 2010 E93 with 75k miles. I change the oil every 5,000 - 7,500 miles (using Liqui Moly Synthetic 5W-30).

Up until a week ago, I've never had to add a drop of oil between changes - the oil level that is displayed on the NAV screen always showed exactly at the max line.

But recently, when I was on a short trip, I just happened to check the oil level, and it was just above the MIN line. Then, just 60 or so miles later, it dropped below the min line, and the system told me that I needed to add a quart. I added a quart, which brought it back up to the max line; but not 100 miles later, the oil level fell again - to just below the max line. I arrived home shortly thereafter, and it's still at that level, but I'm assuming that after another 100 miles or so, I'm going to see another drop in the oil level.

I have no clue as to why all of a sudden the engine seems to be either consuming or losing oil. There is no evidence of any leaks (that I can see from the engine bay or beneath the vehicle - although admittedly, I've not taken anything apart yet), there is no smell of burning oil, nor is there any blue smoke or anything like that coming out of the exhaust.

Have any of you experienced this? Do any of you have any ideas as to what it might be?

Many thanks in advance for your help!!!

[Phil325i]

Could be your OZS is failing. A scan tool should reveal if this is the case...

[Three_thirty_I]

Either you have chronic oil consumption all of a sudden (highly doubtful), or there is some oil consumption as well as some moisture in the oil from the short trips that is confusing the oil level sensor. I avoid short trips with my E90, but some years back I had an odd issue where the oil level reading dropped from the max mark to the 50% in one go (I always check my oil level reading every time I drive, so it is impossible for it to have dropped this much). I drove the car a few times later that day and it kept showing 50% which was really bugging me. Later that night when the roads were quiet, I took the car out for a spirited drive, and all of a sudden the oil level showed 100% briefly, then dropped and stayed on the 75% mark. So I can only assume that it must have burnt off some post winter moisture or something along those lines. Hasn't done this since.

[Efthreeoh]

Not sure what engine you have, but I would leave it alone. The system indicated a +1 QT add condition and you added the quart. If the engine is now reporting an oil level at 3/4 full (of the top quart) then there is sufficient oil in the engine. It has been my experience that the e-dipstick is needs several cycles to determine the true oil level.

[maaaaackle]

Originally Posted by Phil325i

Could be your OZS is failing. A scan tool should reveal if this is the case...

Sorry to digress, but what is the OZS?

[Phil325i]

Originally Posted by maaaaackle

Sorry to digress, but what is the OZS?

The oil level/condition sensor:

BMW-OZS sensor.pdf

[donmcpeters]

Thanks very much to all of you for your thoughts and suggestions regarding this subject. To address some of your questions/comments throughout this thread:

Phil325i: I doubt that the OZS is failing, because a) I'm not getting an error message, and a failing/failed OZS should give an error message; and b) the oil level indicator is in fact functioning normally as far as I can tell. That is to say, when it stated that I needed to add oil - I did in fact need to add oil; and when I did add oil, it registered exactly at the MAX level again.

Three_thirty_I: This vehicle is my daily driver, and as I mentioned, I have never had to add a drop of oil in between changes. Sometimes I only drive it 8 miles a day, and sometimes I take it on "short trips" of under 300 miles to visit my grandchildren, and sometimes I take it on "long trips" of over 1,000 miles. The oil level indicator has always remained exactly at the MAX level no matter what. So whatever is happening is something new, and not because I'm doing anything any different as far as my driving habits, or environmental (moisture) conditions.

Efthreeoh: I have the N52 engine. And I have run many cycles and trips since this began (although they have been several short trips and cycles - I haven't been on the highway again or put many miles on the vehicle since this began). I do realize that 3/4 full is indeed a sufficient amount of oil, but my concern is that after I added a quart, it showed exactly at MAX for about 100 miles, and then dropped again. Something this vehicle has never done. So now I'm monitoring the oil level daily, and waiting for "another shoe to drop" (the oil level to decrease again).

So once again - many thanks to all of you for taking time to respond to this. If you have any other ideas/suggestions, they are most welcome!

[Bamaben]

Make sure an oil pipe to turbo didn't bust

[patents]

Originally Posted by Bamaben

Make sure an oil pipe to turbo didn't bust

He doesn't have turbo.

OP: At the least, next time you change the oil, measure the amount of drained oil. That way you can know for sure how much oil is in there. That's really the only way to know for sure. I would do that before going down too many rabbit holes.

[Efthreeoh]

Originally Posted by donmcpeters

Thanks very much to all of you for your thoughts and suggestions regarding this subject. To address some of your questions/comments throughout this thread:

Phil325i: I doubt that the OZS is failing, because a) I'm not getting an error message, and a failing/failed OZS should give an error message; and b) the oil level indicator is in fact functioning normally as far as I can tell. That is to say, when it stated that I needed to add oil - I did in fact need to add oil; and when I did add oil, it registered exactly at the MAX level again.

Three_thirty_I: This vehicle is my daily driver, and as I mentioned, I have never had to add a drop of oil in between changes. Sometimes I only drive it 8 miles a day, and sometimes I take it on "short trips" of under 300 miles to visit my grandchildren, and sometimes I take it on "long trips" of over 1,000 miles. The oil level indicator has always remained exactly at the MAX level no matter what. So whatever is happening is something new, and not because I'm doing anything any different as far as my driving habits, or environmental (moisture) conditions.

Efthreeoh: I have the N52 engine. And I have run many cycles and trips since this began (although they have been several short trips and cycles - I haven't been on the highway again or put many miles on the vehicle since this began). I do realize that 3/4 full is indeed a sufficient amount of oil, but my concern is that after I added a quart, it showed exactly at MAX for about 100 miles, and then dropped again. Something this vehicle has never done. So now I'm monitoring the oil level daily, and waiting for "another shoe to drop" (the oil level to decrease again).

So once again - many thanks to all of you for taking time to respond to this. If you have any other ideas/suggestions, they are most welcome!

You can look into it in my posts, it's a long story, but I have a lot of experience with the oil sensor and how it works, and I published the DIY on how to replace it. It's a simple electrical device that really is not prone to breaking, or providing false oil levels. I've measured my oil quantity at least 5 times over the 22 oil changes I've done, and every time the reported oil level at the oil change was what came out of the engine when I measured it. It's possible the oil level at the +1 QT notification was actually a bit lower (1/4 qt) than just 1 quart, so when you added the quart, the system finally determined it was still 1/4 low. But again, the engine is designed to run with less than 7 quarts of oil and your engine is in the safe oil level zone, so leave it be.